1. Field of the Invention
The present invention relates to sawbucks, and in particular to light weight, collapsible, portable sawbucks.
2. Description of the Related Art
There are numerous designs for sawbucks in the prior art. Since these apparatus are frequently used by professional craftsmen such as carpenters, etc., many of these apparatus are designed to be portable. A major consideration in designing a portable sawbuck (as in any portable device) is to achieve structural stability with a minimum amount of weight. In order to be of the most use to a craftsman, a sawbuck must also be sturdy in use, and capable of withstanding forces applied from many different directions. Additionally, it is desirable that the sawbuck be capable of supporting a large amount of weight (for example, hundreds of pounds) without any substantial deflection or loss of stability.
U.S. Pat. No. 4,386,677 to Gulezian discloses a portable sawbuck having two pairs of X-shaped foldable legs attached to each other by a single metal, pipe-like axle or cross bar. The foldable legs can be formed from commercially available lumber such as 2.times.4s or 2.times.6s. A cross-brace, which can also be a hollow metal pipe, is attached between the inner legs of each pair of X-shaped foldable legs. Lugs are provided on plates which are attached to the inner legs of each leg pair to prevent the sawbuck from collapsing during use.
The transmission of force from the legs to the pipe-like axle is not direct because the wooden legs are attached to the pipe-like axle by the metal plates (which are attached to the legs by screws), each of which acts as a transition piece from the legs to the pipe-like axle. Accordingly, force is transmitted from the legs to the metal plate via the screws attaching the plate to the legs, concentrating most of the force in the portions of the legs receiving the screws. Additionally, the lugs provided on the plates to prevent the sawbuck from collapsing during use are located close to the center of rotation of the legs about the pipe-like axle, and consequently they must counteract a disproportionate amount of shear stress. Accordingly, the lugs must be welded to or cast unitarily with the plates. Furthermore, in order to limit the inward movement of the legs relative to the pipe-like axle, collars are welded to the axle. Accordingly, the sawbuck of Gulezian requires specialized fabrication (welding and metal mill work), increasing its cost and weight. An additional support structure on the pipe-like axle is also required in order to provide a flat work surface for supporting short pieces of work.
U.S. Pat. No. 3,034,546 to Parsons discloses a collapsible sawbuck having three pairs of metal legs with each leg pair having a pin joint for pivotally attaching the legs of a pair together. The leg pairs are attached to each other by disposing an angle-iron under each set of legs on each side of the sawbuck. The sawbuck is preventing from collapsing by chains or other suitable means attached between the angle-irons.
Due to the attachment of the angle-irons to the lowest surface of each leg, the sawbuck is seated along the entire length of each angle-iron on both sides. This construction makes for unstable bearing on uneven surfaces, which will cause the sawbuck to rock if used on uneven surf aces. Additionally, unless extremely strong welded connections can be provided between the legs and the angle-irons, the sawbuck of Parsons lacks rigidity, especially to forces applied in the direction parallel to the angle-irons. At any rate, a large amount of stress is concentrated in the welded joints between the legs and angle-iron due to the cantilever arrangement between each leg and its respective angle-iron. As with the device of Gulezian, specialized fabrication (i.e., welding) is required, thus increasing cost and weight. Additionally, the sawbuck of Parsons lacks versatility in that it is not suitable for providing a flat horizontal work surface or any type of support f or equipment which may be used by a craftsman.
U.S. Pat. No. 4,454,929 to Wellman discloses a collapsible portable sawbuck having three sets of support assemblies connected to one another by two horizontal members located near the lower ends of the support assemblies, and by a third horizontal member fastened to the top portion of each support assembly.
Although suitable for holding timber, the sawbuck of Wellman lacks versatility for the reasons described above with respect to Parsons. The lateral stability of the structure is compromised by the fact that each pivot point operates independently. The main lateral stability mechanism Wellman employs is a third horizontal member located near the top of the structure and is subject to being accidentally cut during use.